The invention generally relates to wireless communication systems. In particular, the invention relates to data detection in a wireless communication system.
FIG. 1 is an illustration of a wireless communication system 10. The communication system 10 has base stations 121 to 125 (12) which communicate with user equipments (UEs) 141 to 143 (14). Each base station 12 has an associated operational area, where it communicates with UEs 14 in its operational area.
In some communication systems, such as code division multiple access (CDMA) and time division duplex using code division multiple access (TDD/CDMA), multiple communications are sent over the same frequency spectrum. These communications are differentiated by their channelization codes. To more efficiently use the frequency spectrum, TDD/CDMA communication systems use repeating frames divided into time slots for communication. A communication sent in such a system will have one or multiple associated codes and time slots assigned to it. The use of one code in one time slot is referred to as a resource unit.
Since multiple communications may be sent in the same frequency spectrum and at the same time, a receiver in such a system must distinguish between the multiple communications. One approach to detecting such signals is joint detection. In joint detection, signals associated with all the UEs 14, users, are detected simultaneously. Approaches for joint detection include zero forcing block linear equalizers (ZF-BLE) and minimum mean square error (MMSE) BLE. The methods to realize ZF-BLE or MMSE-BLE include Cholesky decomposition based and fast Fourier transform (FFT) based approaches. These approaches have a high complexity. The high complexity leads to increased power consumption, which at the UE 14 results in reduced battery life. Accordingly, it is desirable to have alternate approaches to detecting received data.